About Bone Density Tests, Scores, and Why Low Bone Density Doesn’t Mean You’ll Break a Bone

In this post you can learn

• the difference between low bone density and fracture risk
• what your scores mean when you have a bone density scan
• some questions to ask your doctor when you are getting tested for bone density

When you get your results back from a bone mineral density (BMD) test, and your doctor tells you have osteopenia or osteoporosis, it is not a doomed sentence to breaking a bone. Bone mineral density tests, or DXA scans, test one thing – bone mineral density. They do not show how flexible or resilient your bones are, nor the make-up, such as the amount or quality of collagen in your bones.

Fracture risk, on the other hand, is way more complex. It’s dynamic, and changes with lifestyle adjustments. Here are just a few of the factors in fracture risk:

• age
• previous fracture
• gender
• ethnicity
• certain prescription medications
• weight under 127 pounds
• height over 5’7″
• diet
• exercise
• family history
• sleep and stress

Because fracture risk is much more holistic, dynamic and complex, it is harder to measure. 

DEXA scans give you two scores:

T Score compares you to the mean BMD of caucasian women between 20-30 years old. If you are a smaller than average person with smaller than average bones, you will likely have a low bone mineral density score.

Z score compares you to people of your same gender, ethnicity and age range, but not to people of your same height or weight. 

So neither score is truly “apples to apples.”

Here are some other things to know bone health tests.

• If you have lost height, have excess curve in your upper back, or have had back pain, request a Vertebral Fracture Assessment to check the upper spine. This can be done at the same time as your hip and lumbar spine in the DEXA scanner.
• Request a FRAX, fracture risk assessment, for post-menopausal women over 40 who are not taking osteoporosis drugs. Do this before taking any prescription medications.
• If you live in the same place, request your follow up scan to be on the same machine in the same lab. Scanners vary much like scales.
• Request your scan in the same month as your previous one.
• Don’t take calcium supplements on the day of your test.

Even though you cannot control everything about the aging process and your bones, the good news is that you CAN improve your bones and your balance at any age.